1. Field of the Invention
The present invention relates generally to a curtain wall unit to be attached to a building skeleton framework to construct a unit curtain wall and particularly to a curtain wall unit which is superior in weatherproofness.
2. Description of the Prior Art
A unit curtain wall includes a plurality of curtain wall units attached to a building skeleton framework such as slabs or vertical frame members in a checkerboard pattern. The curtain wall units thus attached have respective outer surfaces lying flush with each other and they are aligned vertically and horizontally into the checkerboard pattern. In order to prevent water from infiltrating into the interior, the conventional curtain wall unit has a resilient weatherstrip secured to and around the frame thereof, which weatherstrips have been prefabricated.
However, since the resilient weatherstrip is secured to the frame so as bend roundly at each corner, the resilient weatherstrips of each four adjacent curtain wall units will leave a gap in the juncture where their corners adjoin to each other. Since the conventional curtain wall unit is thus not entirely satisfactory in weatherproofness, watertightness at the junction has been desired at all times.
One attempt to solve the problem is disclosed in Japanese Patent Laid-open Publication No. 62-144311, wherein a kind of backing member is attached to the four adjacent curtain wall units on their rear sides at their juncture. Another attempt is disclosed in Japanese Utility Model Laid-open Publication No. 63-1120, wherein two pairs, vertical and horizontal pairs of weather strips are attached to the vertical and horizontal sides, respectively, of each curtain wall unit and the vertical and horizontal weather strips are joined together at each junction by a crisscross joint member.
However, either of the attempts has drawbacks in that a weak point lies in the junction between the weather strips and the backing member or the crisscross joint member and that the number of parts is increased, causing the cost of the curtain wall unit as a whole to increase and also causing the steps of installation of the unit curtain walls to increase.